Image recording method

ABSTRACT

An image recording method includes applying an ink containing a pigment and polymer particles to a region of a recording medium, and applying a liquid composition capable of destabilizing the dispersion of the pigment in the ink to the recording medium so as to cover at least part of the region of the recording medium. The liquid composition contains 6.0% by mass or more of at least one surfactant selected from the group consisting of the compounds expressed by General Formula (1) and the compounds expressed by General Formula (2) relative to the total mass of the liquid composition. The content of the polymer particles in the ink is 1.0% by mass or more relative to the total mass of the ink.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image recording method.

2. Description of the Related Art

For recording an image, two-liquid reaction systems have been studiedwhich use an ink and a liquid composition containing a reaction agentcapable of destabilizing the dispersion of the pigment in the ink. Amongsuch two-liquid reaction systems, a system using an ink containingpolymer particles has been studied (Japanese Patent Laid-Open Nos.7-32721, 2010-31267, 2010-46918, and 2011-178033).

On the other hand, an image recording method (single-liquid reactionsystem) not using a liquid composition has been studied for recordinghigh-density, high-quality images (Japanese Patent Laid-Open No.2012-92317). This method takes advantage of the nature of the ink itselfto react. Japanese Patent Laid-Open No. 2012-92317 discloses an imagerecording method using an ink containing a pigment, polymer particles,and a block copolymer having an ethylene oxide structure and a propyleneoxide structure. This block copolymer gelates at a specific temperature(gelation temperature) or more. This patent document describes that theink aggregates rapidly by being applied to a recording medium heated tothe gelation temperature or more.

In the studies of the present inventors, however, the image recordingmethods using the two-liquid reaction systems of the above-cited patentdocuments did not provide high-quality images when recording wasperformed at such a high speed as to meet recent demand. Also, in theabove-cited single-liquid reaction system, the apparatus for this methodtends to become large because the recording medium must be heated.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an image recording methodusing a two-liquid reaction system that can provide high-quality imageswithout heating the recording medium.

According to an aspect of the invention, an image recording method isprovided which includes applying an ink containing a pigment and polymerparticles to a region of a recording medium, and applying a liquidcomposition capable of destabilizing the dispersion of the pigment inthe ink to the recording medium so as to cover at least part of theregion of the recording medium. The liquid composition contains 6.0% bymass or more of at least one surfactant selected from the groupconsisting of the compounds expressed by general formula (1) and thecompounds expressed by general formula (2) relative to the total mass ofthe liquid composition. The content of the polymer particles in the inkis 1.0% by mass or more relative to the total mass of the ink.

where l and n are numerals with “l+n” being 3 or more and 45 or less,and m represents a numeral of 16 or more and 57 or less.

where p and r are numerals with “p+r” being 25 or more and 50 or less,and q represents a numeral of 8 or more and 25 or less.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments.

DESCRIPTION OF THE EMBODIMENTS

The present invention will be further described using exemplaryembodiments.

The present inventors investigated why the known two-liquid reactionsystems did not provide high-quality images when recording was performedat such a high speed as to meet recent demand. The results are as below.

Known image recording methods using a two-liquid reaction system aredesigned to increase the reactivity between the ink and the liquidcomposition and thus to prevent blotting or bleeding effectively. Morespecifically, the constituents and their contents of the ink and theliquid composition are controlled so that the pigment can aggregaterapidly when the ink and the liquid composition come into contact witheach other. In a high-speed recording, the time interval between theapplications of the ink and the liquid composition is very small, andaccordingly, the ink and the liquid composition may be mixed in a statein which they are both liquid. The inventors found that if thereactivity between the ink and the liquid composition are excessivelyhigh, a phenomenon (image migration) occurs when they are mixed, inwhich the pigment aggregates to decrease in volume and thevolume-decreased aggregate moves from the region where the ink and theliquid composition have been applied and is fixed to a region differentfrom the desired region.

The present inventors have studied a method for reducing the phenomenonof image migration and reached the concept of the invention. Morespecifically, in an embodiment of the invention, the liquid compositionused in combination with an ink containing a pigment and polymerparticles contains 5% by mass or more of at least one surfactantselected from the group consisting of the compounds expressed by GeneralFormula (1) and the compounds expressed by General Formula (2).

In General Formula (1), l and n are numerals with “l+n” being 3 or moreand 45 or less, and m represents a numeral of 16 or more and 57 or less.

In General Formula (2), p and r are numerals with “p+r” being 25 or moreand 50 or less, and q represents a numeral of 8 or more and 25 or less.

The following mechanism of the combination of the ink and the liquidcomposition produces an advantageous effect.

Although the surfactants expressed by General Formula (1) or (2) have ahydrophilic ethylene oxide structure (CH₂CH₂O) and a less hydrophilicpropylene oxide structure (CH₂CH(CH₃)O), thus acting as a surfactant,the function of these surfactants is weaker than typical surfactants.Therefore, when a surfactant of General Formula (1) or (2) is presentwith a pigment or polymer particles, the surfactant is likely to adsorbthe surfaces of the pigment particles or polymer particles rather thanis oriented to the gas-liquid interface. When the ink and the liquidcomposition are mixed, therefore, aggregation reaction of the pigmentand polymer particles of the ink occurs with the surfactant of generalformula (1) or (2) adsorbed to the surfaces of the pigment and polymerparticles. At this time, while the aggregation reaction itself occursrapidly, the volume of the aggregate is unlikely to decrease because thesurfactant is confined among the pigment and polymer particles.Probably, image migration is thus suppressed.

The studies of the present inventors teach that when the content of thesurfactant, or at least one surfactant selected from the groupconsisting of the compounds of General Formulas (1) and (2), in theliquid composition is 6.0% by mass or more while the content of thepolymer particles in the ink is 1.0% by mass or more, image migrationcan be suppressed effectively. If the surfactant content is less than6.0% by mass, or if the polymer particles content in the ink is lessthan 1.0%, the aggregate decreases in volume and results in imagemigration.

As in such a mechanism, the constituents and their contents of the inkand liquid composition interact synergetically with each other and thusproduce an effect advantageous in solving the issue described above.

Image Recording Method

The image recording method according to an embodiment of the inventionincludes Step (A) of applying the ink to a region of a recording medium,and Step (B) of applying the liquid composition to the recording mediumso as to cover at least part of the region to which the ink is applied.

In the present embodiment, the ink may be applied by an ink jetrecording method that includes the step of discharging the ink from anink jet recording head according to recording signals. In particular, anink jet recording method is advantageous in which the ink is dischargedthrough ejection openings of a recording head by thermal energy appliedto the ink. The liquid composition is applied to the recording mediumby, for example, an ink jet method or a coating method. Exemplarytechniques for the coating method include roller coating, bar coating,and spray coating. The term “recording” mentioned herein includes theoperation of recording on a recording medium such as glossy paper orplain paper, and the operation of printing on an impermeable recordingmedium such as a glass or plastic sheet or a plastic film.

In the present embodiment, Step (A) may be performed before Step (B), orStep (B) may be performed before Step (A). Also, if the same step isperformed twice or more, the two steps may be performed, for example, inthis order: Step (A), Step (B), and Step (A); or Step (B), Step (A) andStep (B). In particular, the operation of performing Step (A) after Step(B) is advantageous in enhancing image quality.

Set of Ink Jet Ink and Liquid Composition

The ink used in the present embodiment in combination with the liquidcomposition is not particularly limited, and may be a cyan ink, amagenta ink, a yellow ink, or a black ink. An image recording method ofthe present embodiment and a set of an ink and a liquid composition usedin the image recording method will now be described. In the followingdescription, “(meth)acrylic acid” refers to acrylic acid and methacrylicacid, and “(meth)acrylate” refers to acrylate and methacrylate.

Ink

The ink used in the image recording method of the present embodimentcontains a pigment and polymer particles.

Resin Particles

The polymer particles mentioned herein refer to a polymer havingparticle sizes dispersed in a solvent. In the present embodiment, theparticle size of the polymer particles is preferably 10 nm or more and1,000 nm or less, and more preferably 100 nm or more and 500 nm or less,in terms of volume median particle size (D₅₀). The median particle sizeD₅₀ of the polymer particles can be measured as below. The dispersion ofthe polymer particles is diluted to 50 times (on a volume basis) withpure water and subjected to measurement with UPA-EX150 (manufacture byNikkiso) under the conditions: SetZero of 30 s; number of measurementsof 3; measurement time of 180 s; and refractive index of 1.5.

Preferably, the polymer particles have a polystyrene-equivalent weightaverage molecular weight of 1,000 or more and 2,000,000 or more,measured by gel permeation chromatography (GPC).

The content of the polymer particles in the ink is 1.0% by mass or morerelative to the total mass of the ink. Preferably, the polymer particlecontent in the ink is 1.0% by mass or more and 50.0% by mass or less,such as 2.0% by mass or more and 40.0% by mass or less, relative to thetotal mass of the ink.

In addition, the mass ratio of the polymer particles to the pigment inthe ink is preferably 0.2 or more and 20 or less.

Any polymer particles may be used in the ink of the present embodimentas long as under the above-mentioned condition. For producing thepolymer particles, any monomers can be used, as long as capable of beingpolymerized by emulsion polymerization, suspension polymerization,dispersion polymerization, or the like. Exemplary polymer particles,different in monomer, include particles of acrylic polymer, vinylacetate polymer, ester, ethylene, urethane polymer, synthetic rubber,vinyl chloride polymer, vinylidene chloride polymer, and olefin polymer.Among these, acrylic polymer particles and urethane polymer particlesare advantageous.

The polymer particles may be made of an anionic polymer. Anionic polymerparticles can react with a reaction agent in the liquid composition,described later, to facilitate the aggregation of the polymer particles.

For acrylic polymer particles, exemplary monomers includeα,β-unsaturated carboxylic acids and salts thereof, such as(meth)acrylic acid, maleic acid, crotonic acid, angelic acid, itaconicacid, and fumaric acid; α,β-unsaturated carboxylic acid esters, such asethyl (meth)acrylate, methyl (meth)acrylate, butyl (meth)acrylate,methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, diethyleneglycol (meth)acrylate, triethylene glycol (meth)acrylate, tetraethyleneglycol (meth)acrylate, polyethylene glycol (meth)acrylate,methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol(meth)acrylate, methoxytetraethylene glycol (meth)acrylate,methoxypolyethylene glycol (meth)acrylate, cyclohexyl (meth)acrylate,isobornyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate,monobutyl maleate, and dimethyl itaconate; α,β-unsaturated carboxylicacid alkylamides, such as (meth)acrylamide, dimethyl(meth)acrylamide,N,N-dimethylethyl(meth)acrylamide, N,N-dimethylpropyl(meth)acrylamide,isopropyl(meth)acrylamide, diethyl(meth)acrylamide, (meth)acryloylmorpholine, maleic acid monoamide, and crotonic acid methylamide; arylgroup-containing α,β-ethylenic unsaturated compounds, such as styrene,α-methylstyrene, phenylvinyl acetate, benzyl (meth)acrylate, and2-phenoxyethyl (meth)acrylate; and esters of polyfunctional alcohols,such as ethylene glycol diacrylate and polypropylene glycoldimethacrylate. The polymer particles may be made of a homopolymerproduced by polymerizing one of these monomers, or a copolymer producedby polymerizing two or more of these monomers. If the polymer particlesare made of a copolymer, the copolymer may be a random copolymer or ablock copolymer. In particular, polymer particles made of a copolymer ofa hydrophilic monomer and a hydrophobic monomer are advantageous. Thehydrophilic monomer may be an α,β-unsaturated carboxylic acid or a saltthereof, and the hydrophobic monomer may be an α,β-unsaturatedcarboxylic acid ester or an α,β-ethylenic unsaturated compound having anaryl group.

Urethane polymer particles are produced by a reaction of apolyisocyanate compound, which has two or more isocyanate groups, and apolyol compound, which has two or more hydroxy groups. In the presentembodiment, any of the urethane polymer particles produced by a reactionof a known polyisocyanate compound and a known polyol compound can beused as long as the particle size is within the above-mentioned range.

In structure, the polymer particles may have a single layer structure ora multilayer structure such as a core-shell structure. In the presentembodiment, multilayer particles are advantageous. Resin particleshaving a core-shell structure are particularly advantageous. In polymerparticles having a core-shell structure, the core portions and the shellportions have definitely different functions from each other. Resinparticles having such a core-shell structure are advantageous inimparting more functions to the ink than polymer particles having asingle-layer structure.

Pigment

In the present embodiment, any known pigments may be used as thepigment. The pigment content in the ink is preferably 0.5% by mass ormore and 15.0% by mass or less, more preferably 1.0% by mass or more and10.0% by mass or less, relative to the total mass of the ink.

The pigment may be of polymer-dispersed type that is dispersed with apolymer dispersant (polymer-dispersed pigment using a polymerdispersant, microencapsulated pigment including polymer particles whosesurfaces are coated with a polymer, or polymer-bonded pigment includingpolymer particles having organic groups of a polymer chemically bondedto the surfaces thereof), or may be of self-dispersing type whoseparticles have hydrophilic groups at the surfaces thereof(self-dispersing pigment). Two or more pigments different in state ofdispersion may be used in combination. Exemplary pigments include carbonblack and organic pigments. The pigment may be composed of a singlepigment or may contain two or more pigments. If the pigment is ofpolymer dispersed type, a polymer is used as a dispersant. The moleculeof the polymer used as the dispersant desirably has a hydrophilic siteand a hydrophobic site. Examples of such a polymer include acrylicpolymer produced by polymerization using a monomer having a carboxygroup, such as acrylic acid or methacrylic acid, and urethane polymerproduced by polymerization using a diol having an anionic group, such asdimethylolpropionic acid.

The polymer used as a dispersant has an acid value, preferably, 50 mgKOH/g or more and 550 mg KOH/g or less. The polystyrene-equivalentweight average molecular weight (Mw), measured by gel permeationchromatography (GPC), of the polymer dispersant is preferably 1,000 ormore and 50,000 or less.

The polymer dispersant content in the ink may be 0.1% by mass or moreand 10.0% by mass or less, preferably 0.2% by mass or more and 4.0% bymass or less. The mass ratio of the polymer dispersant to the pigment ispreferably 0.1 or more and 3.0 or less.

Aqueous Medium

The ink may contain water or an aqueous medium that is a mixture ofwater and a water-soluble organic solvent. If the ink contains anaqueous medium, the water-soluble organic solvent content is preferably3.0% by mass or more and 50.0% by mass or less relative to the totalmass of the ink. Any conventionally used water-soluble organic solventscan be used as the water-soluble organic solvent. Exemplarywater-soluble organic solvents include alcohols, glycols, alkyleneglycols containing an alkylene group having a carbon number of 2 to 6,polyethylene glycols, nitrogen-containing compounds, andsulfur-containing compounds. These water-soluble organic solvents may beused singly or in combination as required. If the ink contains water,the water is desirably deionized water (ion exchanged water). In thisinstance, the water content is preferably 50.0% by mass or more and95.0% by mass or less relative to the total mass of the ink.

Other Constituents

The ink may further contain a water-soluble organic compound that issolid at room temperature, such as trimethylolpropane, trimethylolethaneor any other polyhydric alcohol, or urea, ethyleneurea or any other ureaderivative, if necessary. Furthermore, the ink may optionally containother additives, such as a surfactant, a pH adjuster, a corrosioninhibitor, a preservative, an antifungal agent, an antioxidant, anantireductant, an evaporation promoter, a chelating agent, and a polymerother than the above-described polymer particles.

Liquid Composition

The liquid composition is desirably colorless, milky-white or white soas not to affect images recorded with the ink. Accordingly, theabsorbance of the liquid composition for wavelengths of visible light of400 nm or more and 800 nm or less is desirably such that the ratio ofthe highest absorbance to the lowest absorbance (highestabsorbance/lowest absorbance) is 1.0 or more and 2.0 or less. Thissuggests that the absorbance spectrum of the liquid composition hassubstantially no peak in the visible region. Even if a peak isexhibited, the intensity of the peak is very low. In addition, theliquid composition desirably does not contain a coloring material. Theabsorbance of the liquid composition can be obtained by measuring theliquid composition as it is using Hitachi Double Beam SpectrophotometerU-2900 (manufactured by Hitachi High-Technologies). For measuring theabsorbance, the liquid composition may be diluted. The highestabsorbance and the lowest absorbance are both proportional to dilutionrate, and the ratio of the highest absorbance to the lowest absorbanceis independent of the dilution rate.

Surfactants Expressed by General Formula (1) or (2)

Surfactants expressed by General Formula (1) or (2) are block copolymershaving an ethylene oxide structure and a propylene oxide structure.

In General Formula (1), l and n are numerals with “l+n” being 3 or moreand 45 or less, and m represents a numeral of 16 or more and 57 or less.

In General Formula (2), p and r are numerals with “p+r” being 25 or moreand 50 or less, and q represents a numeral of 8 or more and 25 or less.

In the present embodiment, the surfactants expressed by General Formula(1) are more advantageous, and it is more advantageous that l+n is 3 ormore and 15 or less and m is 16 or more and 31 or less.

In the present embodiment, the content of the surfactant of GeneralFormula (1) or (2) (surfactant content) in the liquid composition is6.0% by mass or more relative to the total mass of the liquidcomposition. Preferably, the surfactant content is 20% by mass or more,more preferably 30% by mass or more. Furthermore, the surfactant contentis 70% by mass or less from the viewpoint of the reactivity between theink and the liquid composition. Hence, the surfactant content in theliquid composition is preferably 20% by mass or more and 70% by mass orless relative to the total mass of the liquid composition.

Also, in the image recording method of the present embodiment, the inkand the liquid composition may be applied to a recording medium suchthat the proportion of the amount of the surfactant of the liquidcomposition applied to the recording medium is 4 parts by mass or moreand 160 parts by mass or less, preferably 15 parts by mass or more and140 parts by mass or less, relative to the amount of the polymerparticles of the ink applied to the recording medium.

Reaction Agent

The liquid composition used in the present embodiment may contain areaction agent that will destabilize the dispersion of the pigment inthe ink. The reaction agent may be selected from known materials and is,advantageously, at least one material selected from the group consistingof organic acids and polyvalent metal ions. A plurality of compounds maybe used as the reaction agent.

Examples of the polyvalent metal ions include divalent metal ions, suchas Ca²⁺, Cu²⁺, Ni²⁺, Mg²⁺, Sr²⁺, Ba²⁺, and Zn²⁺; and trivalent metalions, such as Fe³⁺, Cr³⁺, Y³⁺, and Al³⁺. Polyvalent metal ions can beadded in a hydroxide form or a chloride salt form to the liquidcomposition, and may be produced by dissociation. The polyvalent ioncontent is preferably 3% by mass or more and 90% by mass or lessrelative to the total mass of the liquid composition.

Examples of the organic acids include oxalic acid, polyacrylic acid,formic acid, acetic acid, propionic acid, glycolic acid, malonic acid,malic acid, maleic acid, ascorbic acid, levulinic acid, succinic acid,glutaric acid, glutamic acid, fumaric acid, citric acid, tartaric acid,lactic acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid,pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid,coumalic acid, thiophenecarboxylic acid, nicotinic acid, oxysuccinicacid, and dioxysuccinic acid. The organic acid content is preferably 3%by mass or more and 99% by mass or less relative to the total mass ofthe liquid composition.

Aqueous Medium

The liquid composition of the present embodiment may contain water or anaqueous medium that is a mixture of water and a water-soluble organicsolvent. If the liquid composition contains a water-soluble organicsolvent, the water-soluble organic solvent content is preferably 3.0% bymass or more and 50.0% by mass or less relative to the total mass of theliquid composition. Any conventionally used water-soluble organicsolvents can be used as the water-soluble organic solvent. Exemplarywater-soluble organic solvents include alcohols, glycols, alkyleneglycols containing an alkylene group having a carbon number of 2 to 6,polyethylene glycols, nitrogen-containing compounds, andsulfur-containing compounds. These water-soluble organic solvents may beused singly or in combination as required. If the liquid compositioncontains water, the water is desirably deionized water (ion exchangedwater). In this instance, the water content is preferably 50.0% by massor more and 95.0% by mass or less relative to the total mass of theliquid composition.

Other Constituents

The liquid composition may further contain a water-soluble organiccompound that is solid at room temperature, such as trimethylolpropane,trimethylolethane or any other polyhydric alcohol, or urea, ethyleneureaor any other urea derivative, if necessary. Furthermore, the liquidcomposition may optionally contain other additives, such as a surfactantother than the surfactants expressed by General Formula (1) or (2), a pHadjuster, a corrosion inhibitor, a preservative, an antifungal agent, anantioxidant, an antireductant, an evaporation promoter, a chelatingagent, and a polymer.

EXAMPLES

The invention will be further described in detail with reference toExamples and Comparative Examples. However, the invention is not limitedto the following Examples. In the following Examples, “part(s)” is on amass basis unless otherwise specified.

Preparation of Inks

Preparation of Pigment Dispersions

Preparation of Black Pigment Dispersion

A batch type vertical sand mill (manufactured by Aimex) was charged witha mixture of 10 parts of carbon black (product name: Monarch 1100,produced by Cabot), 15 parts of a polymer solution (containing 20.0% bymass of styrene-ethyl acrylate-acrylic acid copolymer (acid value: 150,weight average molecular weight: 8,000) in water, neutralized with anaqueous solution of potassium hydroxide), and 75 parts of pure water,and the materials were dispersed in each other with 200 parts ofzirconia beads of 0.3 mm in diameter for 5 hours while being cooled withwater. The resulting dispersion liquid was centrifuged to remove coarseparticles, and thus a black pigment dispersion containing 10.0% by massof pigment was prepared.

Preparation of Cyan Pigment Dispersion

A cyan pigment dispersion containing 10.0% by mass of a pigment wasprepared in the same manner as in the preparation of the black pigmentdispersion, except that C. I. Pigment Blue 15:3 was used as the pigmentinstead of carbon black.

Preparation of Magenta Pigment Dispersion

A magenta pigment dispersion containing 10.0% by mass of a pigment wasprepared in the same manner as in the preparation of black pigmentdispersion, except that C. I. Pigment Red 122 was used as the pigmentinstead of carbon black.

Preparation of Resin Particle Dispersion

The mixture of 18 parts of ethyl methacrylate, 2 parts of2,2′-azobis-(2-methylbutyronitrile), and 2 parts of n-hexadecane wasstirred for 0.5 hour. The mixture was dropped to 78 parts of 6% aqueoussolution of styrene-butyl acrylate-acrylic acid copolymer (acid value:130 mg KOH/g, weight average molecular weight: 7,000), followed bystirring for 0.5 hour. Then, the resulting mixture was subjected tosupersonic wave irradiation for 3 hours. Subsequently, the mixture wassubjected to a polymerization reaction for 4 hours in a nitrogenatmosphere at 80° C., followed by cooling at room temperature. Thereaction product was filtered to yield a polymer particle dispersionwith a polymer content of 40.0% by mass. The polymer particles in thedispersion had a weight average molecular weight of 250,000, and anaverage particle size (D₅₀) of 200 nm.

Surfactants

Surfactants shown in Tables 1 and 2 were used. In the column of productname in the Tables, Pluronics are products of Adeka. Also, Newpol PE-78is a surfactant produced by Sanyokasei.

TABLE 1 Surfactants Expressed by General Formula (1)

  General Formula (1) Ethylene oxide structure Propylene oxide structureSurfactant No. Product name l + n m Surfactant 1-1 Pluronic L31 3.0 16.4Surfactant 1-2 Pluronic L34 14.0 16.4 Surfactant 1-3 Pluronic L61 5.330.2 Surfactant 1-4 Pluronic P84 43.9 38.8 Surfactant 1-5 Pluronic P10337.1 56.0 Surfactant 1-6 Pluronic L101 12.1 56.0 Surfactant 1-7 PluronicP85 53.0 38.8 Surfactant 1-8 Pluronic P123 40.5 66.4 Surfactant 1-9Pluronic L23 6.0 12.4 Surfactant 1-10 Newpol PE-78 150.0 35.0

TABLE 2 Surfactants Expressed by General Formula (2)

  General Formula (2) Ethylene oxide structure Propylene oxide structureSurfactant No. Product name q p + r Surfactant 2-1 Pluronic 25R-2 16.647.4 Surfactant 2-2 Pluronic 17R-2 16.6 30.2Preparation of InksPreparation of Black Inks

The above-prepared polymer particle dispersion and pigment dispersionwere mixed with the following materials. The “balance” of ion exchangedwater is an amount in which the sum of the constituents of the inkbecomes 100.0% by mass.

Pigment dispersion (pigment content: 10.0% by mass): 30.0% by mass

Resin particle dispersion (polymer content: 30.0% by mass): X (% bymass) in Table 3.

Glycerin: 10.0% by mass

Acetylenol E 100 (surfactant, produced by Kawaken Fine Chemical): 1.0%by mass

Ion-exchanged water: balance

These materials were sufficiently dispersed in each other, and theresulting mixture was subjected to pressure filtration through amicrofilter having a pore size of 3.0 μm (manufactured by Fujifilm).Thus Black Inks 1 to 6 were prepared.

TABLE 3 Black ink Preparation Conditions Polymer particle dispersionBlack ink Content Polymer particle No. Type X solid content Black ink 1Polymer particle dispersion 1 16.7 5.0 Black ink 2 Polymer particledispersion 1 33.2 10.0 Black ink 3 Polymer particle dispersion 2 16.75.0 Black ink 4 — 0 0 Black ink 5 Polymer particle dispersion 1 3.3 1.0Black ink 6 Polymer particle dispersion 1 2.0 0.6Preparation of Cyan Inks and Magenta Inks

Cyan Inks 1 to 6 and Magenta Inks 1 to 6 were prepared in the samemanner as the Black Inks described above, except that the cyan pigmentdispersion or the magenta pigment dispersion was used instead of theblack pigment dispersion.

Preparation of Liquid Compositions

The following materials were sufficiently mixed, and the resultingmixture was subjected to pressure filtration through a microfilterhaving a pore size of 3.0 μm (manufactured by Fujifilm). Thus liquidcompositions were prepared. The “balance” of ion exchanged water is anamount in which the sum of the constituents of the liquid compositionbecomes 100.0% by mass.

Reagent (see Table 4): Y (% by mass) in Table 4

Potassium hydroxide (neutralizer): 3.0% by mass

Surfactant (see Table 4): Z (% by mass) in Table 4

Acetylenol E 100 (surfactant, produced by Kawaken Fine Chemical): 1.0%by mass

Ion-exchanged water: balance

TABLE 4 Liquid composition preparation conditions Surfactant expressedby General Formula Reagent (1) or (2) Liquid Con- Con- composition tenttent No. Compound Y Type Z Liquid composition 1 Glutaric acid 21.0Surfactant 1-1 40.0 Liquid composition 2 Glutaric acid 21.0 Surfactant1-2 40.0 Liquid composition 3 Glutaric acid 21.0 Surfactant 1-3 40.0Liquid composition 4 Glutaric acid 21.0 Surfactant 1-4 40.0 Liquidcomposition 5 Glutaric acid 21.0 Surfactant 1-5 40.0 Liquid composition6 Glutaric acid 21.0 Surfactant 1-6 40.0 Liquid composition 7 Glutaricacid 21.0 Surfactant 2-1 40.0 Liquid composition 8 Glutaric acid 21.0Surfactant 2-2 40.0 Liquid composition 9 Glutaric acid 21.0 Surfactant1-1 5.0 Liquid composition 10 Glutaric acid 21.0 Surfactant 1-1 20.0Liquid composition 11 Glutaric acid 21.0 Surfactant 1-1 70.0 Liquidcomposition 12 Glutaric acid 21.0 Surfactant 1-1 75.0 Liquid composition13 Levulinic acid 42.0 Surfactant 1-1 40.0 Liquid composition 14 Malonicacid 21.0 Surfactant 1-1 40.0 Liquid composition 15 Calcium 21.0Surfactant 1-1 40.0 chloride Liquid composition 16 Glutaric acid 21.0 —0 Liquid composition 17 Glutaric acid 21.0 Surfactant 1-7 40.0 Liquidcomposition 18 Glutaric acid 21.0 Surfactant 1-8 40.0 Liquid composition19 Glutaric acid 21.0 Surfactant 1-9 40.0 Liquid composition 20 Glutaricacid 21.0 Surfactant 1-10 40.0 Liquid composition 21 Glutaric acid 21.0Surfactant 1-1 3.0 Liquid composition 22 Glutaric acid 21.0 Surfactant1-1 6.0Evaluation of Images

The ink cartridges charged with the inks prepared above were mounted onan image recording apparatus. In the image recording apparatus used forthe evaluation, the recording duty of 100% was a condition where onedroplet of 3.0 ng of ink is applied to a unit region of 1/1,200 inch×1/1,200 inch at a resolution of 1,200 dpi×1,200 dpi. Images wererecorded in a manner described below, and the quality of the images wasevaluated by examining the variation in dot size and the occurrence ofimage migration. Examination processes and Evaluation criteria were asfollows: When either the variation in dot size (diameter) or theoccurrence of image migration was rated as C or D, the image quality wasjudged to be low and unacceptable. The results are shown in Table 5.

Variation in Dot Size

First, each liquid composition was applied to a recording medium (PearlCoat, manufactured by Mitsubishi Paper Mills) with a coating roller atan application rate of 1.0 g/m², using the above-described imagerecording apparatus. Then, a cyan ink was discharged onto the resultingrecording medium from an ink jet recording head, thus recording an image(5 cm×5 cm solid pattern) with a recording duty of 100%. Furthermore, ablack ink was applied to the region where the solid pattern of the cyanink was recorded and a region of the recording medium where the solidpattern was not recorded. The dot size (diameter) d₁ of the black ink inthe region of the cyan solid pattern and the dot size (diameter) d₂ ofthe black ink in the region where the cyan solid patter was not printedwere measured, and the dot size ratio (=100×|d₁−d₂|/d₁) was calculated.The results were rated according to the following criteria:

AA: Dot size ratio was less than 5.

A: Dot size ratio was 5 or more and less than 10.

B: Dot size ratio was 10 or more and less than 15.

C: Dot size ratio was 15 or more and less than 20.

D: Dot size ratio was 20 or more.

Occurrence of Image Migration

First, each liquid composition was applied to a recording medium (PearlCoat, manufactured by Mitsubishi Paper Mills) with a coating roller atan application rate of 1.0 g/m², using the above-described imagerecording apparatus. Then, a black ink, a cyan ink and a magenta inkwere discharged onto the recording medium having the coating of theliquid composition from an ink jet recording head, thus recording animage (5 cm×5 cm solid pattern) with a recording duty of 300% (100% foreach ink). The resulting image was checked for missing color through amicroscope. If image migration occurs, a missing color is observed inthe solid pattern. The rating criteria were as follows:

A: No missing color was observed.

B: Missing color was observed, but was at an acceptable level.

C: Marked missing color was observed.

TABLE 5 Evaluation of Ink-Liquid Composition Combinations EvaluationBlack Cyan Magenta Liquid Dot size Image Example No. ink No. ink No. inkNo. composition No. Variation migration Example 1 Black Cyan MagentaLiquid A A ink 1 ink 1 ink 1 composition 1 Example 2 Black Cyan MagentaLiquid A A ink 1 ink 1 ink 1 composition 2 Example 3 Black Cyan MagentaLiquid A A ink 1 ink 1 ink 1 composition 3 Example 4 Black Cyan MagentaLiquid B A ink 1 ink 1 ink 1 composition 4 Example 5 Black Cyan MagentaLiquid B A ink 1 ink 1 ink 1 composition 5 Example 6 Black Cyan MagentaLiquid B A ink 1 ink 1 ink 1 composition 6 Example 7 Black Cyan MagentaLiquid A B ink 1 ink 1 ink 1 composition 7 Example 8 Black Cyan MagentaLiquid A B ink 1 ink 1 ink 1 composition 8 Example 9 Black Cyan MagentaLiquid A A ink 1 ink 1 ink 1 composition 10 Example 10 Black CyanMagenta Liquid A A ink 1 ink 1 ink 1 composition 11 Example 11 BlackCyan Magenta Liquid B A ink 1 ink 1 ink 1 composition 12 Example 12Black Cyan Magenta Liquid A A ink 2 ink 2 ink 2 composition 1 Example 13Black Cyan Magenta Liquid A A ink 1 ink 1 ink 1 composition 13 Example14 Black Cyan Magenta Liquid A A ink 1 ink 1 ink 1 composition 14Example 15 Black Cyan Magenta Liquid A B ink 1 ink 1 ink 1 composition15 Example 16 Black Cyan Magenta Liquid A A ink 3 ink 3 ink 3composition 1 Example 17 Black Cyan Magenta Liquid A B ink 5 ink 5 ink 5composition 1 Example 18 Black Cyan Magenta Liquid B A ink 1 ink 1 ink 1composition 22 Comparative Black Cyan Magenta Liquid D C Example 1 ink 4ink 4 ink 4 composition 1 Comparative Black Cyan Magenta Liquid D CExample 2 ink 1 ink 1 ink 1 composition 16 Comparative Black CyanMagenta Liquid C B Example 3 ink 1 ink 1 ink 1 composition 17Comparative Black Cyan Magenta Liquid D C Example 4 ink 1 ink 1 ink 1composition 18 Comparative Black Cyan Magenta Liquid C C Example 5 ink 1ink 1 ink 1 composition 19 Comparative Black Cyan Magenta Liquid D BExample 6 ink 1 ink 1 ink 1 composition 20 Comparative Black CyanMagenta Liquid D B Example 7 ink 1 ink 1 ink 1 composition 21Comparative Black Cyan Magenta Liquid D B Example 8 ink 6 ink 6 ink 6composition 1 Comparative Black Cyan Magenta Liquid C A Example 9 ink 1ink 1 ink 1 composition 9

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2013-162390, filed Aug. 5, 2013, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image recording method comprising: applying anink comprising a pigment and a polymer particle to a region of arecording medium; and applying a liquid composition capable ofdestabilizing the dispersion of the pigment dispersed in the ink to therecording medium so as to cover at least part of the region of therecording medium; wherein the content of the polymer particle is 1.0% bymass or more relative to the total mass of the ink, and wherein theliquid composition comprises at least one surfactant selected from thegroup consisting of the compounds expressed by General Formula (1) andthe compounds expressed by General Formula (2) with a content of 6.0% bymass or more relative to the total mass of the liquid composition:

wherein “l+n” is 3 or more and 45 or less, and m is 16 or more and 57 orless, and

wherein “p+r” is 25 or more and 50 or less, and q is 8 or more and 25 orless.
 2. The image recording method according to claim 1, wherein thecontent of the surfactant in the liquid composition is 20% by mass ormore and 70% by mass or less relative to the total mass of the liquidcomposition.
 3. The image recording method according to claim 1, whereinthe polymer particle in the ink is an anionic polymer particle.
 4. Theimage recording method according to claim 1, wherein the proportion ofthe amount of the surfactant applied to the recording medium is 4 partsby mass or more and 160 parts by mass or less relative to 100 parts bymass of the polymer particles applied to the recording medium.
 5. Theimage recording method according to claim 1, wherein the content of thesurfactant in the liquid composition is 20% by mass or more relative tothe total mass of the liquid composition.
 6. The image recording methodaccording to claim 1, wherein the content of the surfactant in theliquid composition is 30% by mass or more relative to the total mass ofthe liquid composition.
 7. The image recording method according to claim1, wherein the liquid composition comprises a reaction agent fordestabilizing the dispersion of the pigment in the ink.
 8. The imagerecording method according to claim 7, wherein the reaction agent isselected from the group consisting of organic acids and polyvalent metalions.
 9. The image recording method according to claim 1, wherein therecording medium is a paper such as glossy paper or plain paper or animpermeable recording medium such as a glass or plastic sheet or aplastic film.